In retrospect, perhaps getting off with my boss wasn't a career-enhancing move. In the mid-Nineties I was a magazine staff writer responsible for most of the cover stories, and things were going pretty well. Ten months after a one-off fumble, I was made redundant. In my mind, it was easy to prove the two events were linked.

Had I known about my legal standing, I may well have had a good case at an employment tribunal for reinstatement or compensation. But I didn't bother.

Increasingly, however, cases sparked by office affairs and relationships are a nice earner for employment lawyers. One confided that he deals with a large number of cases that never become public, involving famous British business names who become embroiled in affairs with their staff. He arranges settlements with juniors who are quietly moved on to other departments or firms.

'In these highly charged atmospheres, having affairs is more likely and it's seen as an acceptable way of getting on,' says Sarah Veale, head of the Equality and Employment Rights at the TUC. But it's likely that the junior employees, the lower-paid secretary for instance, will be removed when affairs go sour; and this is when you get litigation.

There is evidence that a significant number of directors have benefited from an office affair. A survey out this weekend from TakeLegalAdvice.com reveals that 4 per cent of directors of companies with more than 1,000 employees say either that their career benefited from an affair, or that they promoted a lover.

The growing issue has prompted a number of firms to get new employees to sign 'love contracts'. These compel workers to tell personnel departments if they embark on an affair with a colleague, and to pledge that, should they have a relationship with someone from a rival firm, they won't divulge company secrets.

Barry Mordsley, solicitor and head of employment at Salans in London, has heard of employees who have been sacked for sleeping with the corporate enemy and says that on most occasions firms are vindicated in actions against them. He believes it makes sense for companies to protect themselves by inserting relationship clauses in employee contracts.

This year has shown the destructive nature of relationships at work. Paul Wolfowitz resigned as president of the World Bank after he arranged for his girlfriend, Shaha Riza, a fellow World Bank executive, to get a huge pay increase. In June, shareholders in construction giant Kier voiced concern after it emerged that an affair between the firm's chief executive John Dodds and finance director Deena Mattar created tensions at the company, and played a part in the separation of Dodds from his wife.

The trend is backed up by researchers at Iowa university, who published a study showing how office affairs become unhealthy when they go wrong, becoming associated with depression and a drop in morale. 'When the romance ends, human resource managers anticipate complaints of retaliation (in 17 per cent of cases), stalking (12 per cent), and violence (5 per cent),' says the report.

Mark Vas, 32, a senior manager at a leading City hedge fund, began a relationship with a colleague after he invited her out for a drink. They were outed when on holiday they both rang in to explain that their return flight was delayed. Vas said he would have thought twice about the relationship if there were direct reporting lines between them. Though the relationship has ended, he believes it has not harmed his career. But his former girlfriend now works for a different company, which may tell its own story.